A liquid crystal display device typified by a liquid crystal display panel, a liquid crystal display module or the like is a device that utilizes dielectric anisotropy, optical anisotropy or the like of a liquid crystal compound. As an operating mode of the liquid crystal display device, a variety of modes are known, such as a phase change (PC) mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode, a bistable twisted nematic (BTN) mode, an electrically controlled birefringence (ECB) mode, an optically compensated bend (OCB) mode, an in-plane switching (IPS) mode, a vertical alignment (VA) mode, a multi-domain vertical alignment (MVA) mode and polymer sustained alignment (PSA) mode.
In addition to the displays described above, as a new display mode using a cholesteric liquid crystal having a comparatively short pitch, a proposal has been made on a display that utilizes “flexo-electric” effect. In the displays, the cholesteric liquid crystals are aligned in an arrangement of “helical structure in which helical axes are uniformly aligned in parallel to a substrate” (Uniformed Lying Helix; ULH), and ULH is also used as a name of the display mode. However, in the mode, specific problems to be solved include difficulty of obtaining uniform alignment, high driving voltage, an insufficient contrast ratio and having electrooptical hysteresis.
In a similar manner, as a display mode in place of IPS, a proposal has been made on a display mode including a cholesteric liquid crystal having a short pitch, namely a mode of “helical structure in which helical axes are uniformly aligned vertically to a substrate” (Uniformed Standing Helix: USH) because a superb black level can be exhibited in comparison with other display modes providing a wide viewing angle (for example, an IPS mode or VA mode).
In the USH mode or ULH mode, a proposal has been made on use of the bimesogenic liquid crystal material to allow an electrooptical response by the flexo-electric effect.
For example, GB 2356629 B (Patent literature No. 1) discloses a display device using a bimesogenic compound and utilizing a flexo-electric effect. In the display devices, the bimesogenic compound exhibits several advantages over an ordinary monomesogenic compound, and examples thereof include a higher flexo-electric coefficient, and a tilt angle per unit electric field is maximized to be larger by one digit in comparison with the conventional mesogenic compound. Designing of molecules of the bimesogenic compound can cause minimization of dielectric coupling that reduces loosening of a helix, and on the other hand, can cause maximization of the flexo-electric response to allow faster switching and a lower electric field.
JP H10-237004 A (Patent literature No. 2) discloses a bimesogenic compound having a 2,3-difluorophenylene group, including alkylenedioxy compounds as shown in compound (I).

Moreover, Non-patent literature No. 5 discloses a bimesogenic compound having a cyanobiphenyl structure, including alkylenedioxy compounds as shown in compound (II).
